Zinc suppresses apoptosis of U937 cells induced by hydrogen peroxide through an increase of the Bcl-2/Bax ratio

Crosstalk between trace elements and T-cell immunity during early-life health in pigs

With gradual ban on the use of antibiotics, the deficiency and excessive use of trace elements in intestinal health is gaining attention. In mammals, trace elements are essential for the development of the immune system, specifically T-cell proliferation, and differentiation. However, there remain significant gaps in our understanding of the effects of certain trace elements on T-cell immune phenotypes and functions in pigs. In this review, we summarize the specificity, development, subpopulations, and responses to pathogens of porcine T cells and the effects of functional trace elements (e.g., iron, copper, zinc, and selenium) on intestinal T-cell immunity during early-life health in pigs. Furthermore, we discuss the current trends of research on the crosstalk mechanisms between trace elements and T-cell immunity. The present review expands our knowledge of the association between trace elements and T-cell immunity and provides an opportunity to utilize the metabolism of trace elements as a target to treat various diseases.

Interaction between mitophagy, cadmium and zinc

Mitophagy is the selective degradation of mitochondria by autophagy. This process is considered to be one of the stages of mitochondrial quality control, as a result of which damaged depolarized mitochondria are eliminated, thus limiting the formation of reactive oxygen species and the release of apoptogenic factors. Selective degradation of mitochondria by autophagy is one of the main ways to protect cells from cadmium toxicity, which results in dysfunction of the mitochondrial electron transport chain, leading to electron leakage, production of reactive oxygen species and cells death. However, excessive autophagy can be dangerous for cells. Currently, the participation of cadmium ions in normal physiological processes has not been detected. Zn²⁺, unlike Cd²⁺, regulate the activity of a large number of functionally important proteins, including transcription factors, enzymes, and adapters. It has been shown that Zn²⁺ not only participate in autophagy, but are also crucial for basal or induced autophagy. It is likely that zinc drugs can be used to reduce the cadmium toxicity and in the regulation of mithophagy.

Zinc: From Biological Functions to Therapeutic Potential

The trace element zinc (Zn) displays a wide range of biological functions. Zn ions control intercellular communication and intracellular events that maintain normal physiological processes. These effects are achieved through the modulation of several Zn-dependent proteins, including transcription factors and enzymes of key cell signaling pathways, namely those involved in proliferation, apoptosis, and antioxidant defenses. Efficient homeostatic systems carefully regulate intracellular Zn concentrations. However, perturbed Zn homeostasis has been implicated in the pathogenesis of several chronic human diseases, such as cancer, diabetes, depression, Wilson's disease, Alzheimer's disease, and other age-related diseases. This review focuses on Zn's roles in cell proliferation, survival/death, and DNA repair mechanisms, outlines some biological Zn targets, and addresses the therapeutic potential of Zn supplementation in some human diseases.

Effect of zinc and copper ions on cadmium-induced toxicity in rat cultured cortical neurons

BACKGROUND

Cadmium is a highly toxic heavy metal that is capable of accumulating in the body and causing neurodegeneration. However, the effect of other trace elements on Cd²⁺ toxicity is currently poorly understood. The aim of this work was to study the effect of Zn²⁺ and Cu²⁺ ions on cadmium-induced death of neurons in the cerebral cortex.

METHODS

The work was performed on rat cortical primary cultures. The MTT test was used to determine the cytotoxicity effects. Analysis of intracellular Ca²⁺ concentration was assessed by the Fluo-4 AM calcium indicator that exhibit an increase in fluorescence upon binding Ca²⁺. MitoSOX Red (mitochondrial superoxide indicator) was used to measuring mitochondrial ROS content in live cells.

RESULTS

In this article, we show that the administration of CdCl₂ (0.005-0.02 mM) for 48 h induced an increase in dose-dependent death rate of cultured cortical neurons. Mature neurons were more sensitive to the damaging effects of Cd²⁺ than immature ones. ZnCl₂ (0.01-0.03 mM) significantly protected neurons from this toxic effect. In contrast to ZnCl₂, CuCl₂ (0.01 mM) increased cadmium neurotoxicity. Using Fluo-4 AM, measurements of intracellular calcium ions demonstrated that 24 h-exposure to Cd²⁺ induced intensive increase in Fluo-4 fluorescence in neurons, which was significantly reduced by zinc ions. CuCl₂ increased the cadmium-induced Fluo-4 and MitoSOX Red fluorescence in neurons. The chelator of intracellular Ca²⁺ BAPTA significantly decreased Cd²⁺-induced intensive increase in Fluo-4 fluorescence in cells.

CONCLUSION

The data obtained by us indicate that Zn²⁺ and Cu²⁺ can affect the neurotoxicity of cadmium in different directions: Zn²⁺ weaken the violation of intracellular calcium homeostasis caused by cadmium, preventing cell death, while Cu²⁺ potentiate the increase in the level of free intracellular calcium induced by cadmium and the development of mitochondrial dysfunction with an increase in the production of free radicals in differentiated cultured neurons of the cerebral cortex, which ultimately stimulates cytotoxicity.

The Role of Zinc in GM-CSF-Induced Signaling in Human Polymorphonuclear Leukocytes

SCOPE

Zinc is suggested to be necessary for functional signaling induced by certain growth factors. The granulocyte-macrophage colony-stimulating factor (GM-CSF) is a key factor for differentiation and activation of myeloid cells. This report analyses the impact of different zinc concentrations on GM-CSF-induced signaling in mature polymorphonuclear leukocytes (PMN).

METHODS AND RESULTS

As measured by flow cytometry, zinc increases surface GM-CSF receptor (GM-CSFR) in PMN, whereas monocytes respond with decreased GM-CSFR surface expression. Since total cellular GM-CSFR expression remains unaffected, the observed zinc-induced GM-CSFR surface dynamics may be explained by receptor redistribution. In PMN, zinc enhanced phosphorylation of mitogen-activated protein kinases (MAPK) in a dose-dependent manner as found in western blot. Zinc-induced MAPK phosphorylation is additionally augmented by moderate GM-CSF stimulation.

CONCLUSION

The present study demonstrates the opposing influence of zinc on GM-CSFR surface expression in monocytes and PMN. Zinc and GM-CSF, use in optimized concentrations, augment MAPK signaling, and increase expression of MAPK-induced myeloid cell leukemia-1 (Mcl-1) in PMN. Thus, this study concludes that zinc strengthens growth factor-induced signaling. Hence, the study provides a basis for further in vivo studies, focusing on the therapeutic value of zinc in patients with a disturbed GM-CSF signaling.

Functional Analysis of the Promoter Regions of Two Apoptosis-Related Genes (Bcl-2 and Cycs) and Their Regulation by Zn in Yellow Catfish

B-cell lymphoma 2 (Bcl-2) and cytochrome c (Cycs) are two important proteins relevant to cellular apoptosis. In this study, we characterized the functions of the promoter regions of two apoptosis-related genes, Bcl-2 and Cycs, in yellow catfish Pelteobagrus fulvidraco. We obtained a 1989 bp Bcl-2 promoter and an 1830 bp Cycs promoter and predicted several key transcription factor binding sites (TFBSs) on the promoters, such as Kruppel-like factor 4 (KLF4), signal transducer and activator of transcription factor 3 (STAT3), forkhead box O (FOXO), metal-responsive element (MRE) and hepatocyte nuclear factor 1α (HNF-1α). Zinc (Zn) increased the activities of the Bcl-2 promoter but decreased the activities of the Cycs promoter. Metal-responsive transcription factor 1 (MTF-1) and HNF-1α directly bound with Bcl-2 and Cycs promoters, and they positively regulated the activity of the Bcl-2 promoter but negatively regulated the activity of the Cycs promoter. Zn promoted the binding ability of HNF-1α to the Bcl-2 promoter but decreased its binding ability to the Cycs promoter. However, Zn had no significant effect on the binding capability of MTF-1 to the regions of Bcl-2 and Cycs promoters. Zn upregulated the mRNA and total protein expression of Bcl-2 but downregulated the mRNA and total protein expression of Cycs. At the same time, Annexin V-FITC/PI staining showed that Zn significantly reduced the apoptosis of primary hepatocytes. For the first time, our study provides evidence for the MRE and HNF-1α response elements on the Bcl-2 and Cycs promoters, offering new insight into the mechanism by which Zn affects apoptosis in vertebrates.

Non-redox cycling mechanisms of oxidative stress induced by PM metals

Metallic compounds contribute to the oxidative stress of ambient particulate matter (PM) exposure. The toxicity of redox inert ions of cadmium, mercury, lead and zinc, as well as redox-active ions of vanadium and chromium is underlain by dysregulation of mitochondrial function and loss of signaling quiescence. Central to the initiation of these effects is the interaction of metal ions with cysteinyl thiols on glutathione and key regulatory proteins, which leads to impaired mitochondrial electron transport and persistent pan-activation of signal transduction pathways. The mitochondrial and signaling effects are linked by the production of H₂O₂, generated from mitochondrial superoxide anion or through the activation of NADPH oxidase, which extends the range and amplifies the magnitude of the oxidative effects of the metals. This oxidative burden can be further potentiated by inhibitory effects of the metals on the enzymes of the glutathione and thioredoxin systems. Along with the better-known Fenton-based mechanisms, the non-redox cycling mechanisms of oxidative stress induced by metals constitute significant pathways for cellular injury induced by PM inhalation.

Identification, expression profiling and functional characterization of interleukin 11a ortholog from redlip mullet Liza haematocheila: Insight into its roles in the inflammation and apoptosis regulation

Interleukin 11 (IL-11) is a secretory cytokine with pleotropic properties, including anti-inflammatory and anti-apoptotic functions. This study aimed to functionally characterize a teleostean IL-11a ortholog from redlip mullet (LhIL-11a) through bioinformatic analysis, transcriptional expression profiling and protein function assays. The deduced LhIL-11a protein sequence is 200 amino acids long, with a predicted molecular weight of 23.168 kDa. Multiple sequence alignment indicates that LhIL-11a has a typical four-bundle architecture of α-helixes as observed in other IL-11s. The identity-similarity matrix show a higher identity between LhIL-11a and other fish IL-11a sequences. Phylogenetic analysis demonstrated that LhIL-11a falls within a clade including other fish counterparts. In the tissue distribution analysis, the highest constitutive expression of LhIL-11a mRNA was observed in the mullet gastrointestinal tract and brain tissues. Following the challenges with LPS, poly I:C and Lactococcus garvie, the transcription levels of LhIL-11a were significantly upregulated in both PBCs and liver. In the biological functional assay, recombinant LhIL-11a protein showed strong activities of suppressing pro-inflammatory cytokines and apoptotic gene expression in mullet kidney cells and reducing LPS stimulated NO production in murine macrophage cells. Overall, the findings in this study provide the experimental clues to understanding the functional roles of fish IL-11a in inflammation and apoptosis regulation during host defense against invading microbial pathogens.

Protective Effects of Zinc on 2.45 GHz Electromagnetic Radiation-Induced Oxidative Stress and Apoptosis in HEK293 Cells

Several epidemiological studies have shown that exposure to electromagnetic radiation (EMR) can be harmful to human health. The purpose of this study was to examine oxidative parameters and apoptosis induced by EMR in human kidney embryonic cells (HEK293) and to investigate whether zinc (Zn) has protective effect on EMR-induced apoptosis in HEK293 cells. For our experiment, HEK293 cells were divided into four main groups, control, EMR, 50 μM Zn + EMR, and 100 μM Zn + EMR. HEK293 cells of EMR groups were exposed to 2.45 GHz EMR for 1 h. In Zn groups, HEK293 cells were incubated with different concentrations of Zn for 48 h before EMR exposure. Oxidative stress parameters were determined by spectrophotometric method; bcl-2 and caspase-3 were assessed immunohistochemically and TUNEL method was performed for apoptotic activity. EMR group had higher malondialdehyde (MDA) level and lower superoxide dismutase (SOD) activity compared with control group. In Zn-applied groups, MDA was decreased and SOD activity was increased compared with EMR group. The number of the apoptotic cells and caspase-3 immunopositive cells at EMR group was increased significantly compared with the control group, whereas bcl-2 was decreased. Besides, Zn-treated groups showed a significant reduction in the number of apoptotic cells and caspase-3 from that of EMR group, whereas there was an increase in bcl-2 immunopositivity. Our findings show that EMR caused oxidative stress and apoptotic activation in HEK293 cells. Zn seems to have protective effects on the EMR by increasing SOD activity and bcl-2 immunopositivity, decreasing lipid peroxidation and caspas-3 immunopositivity.

Deep Brain Stimulation of the Pedunculopontine Tegmental Nucleus Renders Neuroprotection through the Suppression of Hippocampal Apoptosis: An Experimental Animal Study

The core objective of this study was to determine the neuroprotective properties of deep brain stimulation of the pedunculopontine tegmental nucleus on the apoptosis of the hippocampus. The pedunculopontine tegmental nucleus is a prime target for Parkinson′s disease and is a crucial component in a feedback loop connected with the hippocampus. Deep brain stimulation was employed as a potential tool to evaluate the neuroprotective properties of hippocampal apoptosis. Deep brain stimulation was applied to the experimental animals for an hour. Henceforth, the activity of Caspase-3, myelin basic protein, Bcl-2, BAX level, lipid peroxidation, interleukin-6 levels, and brain-derived neurotrophic factor levels were evaluated at hours 1, 3 and 6 and compared with the sham group of animals. Herein, decreased levels of caspases activity and elevated levels of Bcl-2 expressions and inhibited BAX expressions were observed in experimental animals at the aforementioned time intervals. Furthermore, the ratio of Bcl-2/BAX was increased, and interleukin -6, lipid peroxidation levels were not affected by deep brain stimulation in the experimental animals. These affirmative results have explained the neuroprotection rendered by hippocampus apoptosis as a result of deep brain stimulation. Deep brain stimulation is widely used to manage neuro-motor disorders. Nevertheless, this novel study will be a revelation for a better understanding of neuromodulatory management and encourage further research with new dimensions in the field of neuroscience.

Why is it worth testing the ability of zinc to protect against ischaemia reperfusion injury for human application

Ischaemia (interruption in the blood/oxygen supply) and subsequent damage induced by reperfusion (restoration of blood/oxygen supply) ultimately leads to cell death, tissue injury and permanent organ dysfunction. The impact of ischaemia reperfusion injury (IRI) is not limited to heart attack and stroke but can be extended to patients undergoing surgeries such as partial nephrectomy for renal cancer, liver resection for colorectal cancer liver metastasis, cardiopulmonary bypass, and organ transplantation. Unfortunately, there are no drugs that can protect organs against the inevitable peril of IRI. Recent data show that a protocol incorporating specific Zn formulation, dosage, number of dosages, time of injection, and mode of Zn delivery (intravenous) and testing of efficacy in a large preclinical sheep model of IRI strongly supports human trials of Zn preconditioning. No doubt, scepticism still exists among funding bodies and research fraternity on whether Zn, a naturally occurring metal, will work where everything else has failed. Therefore, in this article, we review the conflicting evidence on the promoter and protector role of Zn in the case of IRI and highlight factors that may help explain the contradictory evidence. Finally, we review the literature related to the knowledge of Zn's mechanism of action on ROS generation, apoptosis, HIF activation, inflammation, and signal transduction pathways, which highlight Zn's likelihood of success compared to various other interventions targeting IRI.

Depletion of Endogenous Zinc Stores Induces Oxidative Stress and Cell Death in Human Melanoma Cells

The role of intracellular free zinc and its chelation by TPEN (N,N,N’,N’-tetrakis(2–pyridylmethyl)ethylenediamine) was studied in Bowes human melanoma cells. The content of free Zn pools was determined by fluorescent probe Zinquin. Depletion of zinc triggered apoptosis confirmed by cell blebbing, changes in mitochondrial transmembrane potential and GSH levels, caspase-3 activation and nuclear fragmentation. Apoptosis was only partially prevented by cyclosporin A or N-acetylcystein, suggesting various independent but likely interrelated mechanisms participating in this process.

Cladophora glomerata methanolic extract decreases oxidative stress and improves viability and mitochondrial potential in equine adipose derived mesenchymal stem cells (ASCs)

Reactive oxygen species (ROS) are key mediators of several cellular damage and thus associated with equine diseases such as inflammation and metabolic syndrome. This study aimed to evaluate the protective and antioxidant activities of methanolic extract prepared from Cladophora glomerata (C. glomerata) biomass, on equine adipose derived mesenchymal stem cells (EqASCs), under experimental oxidative stress induced by H₂O₂. Pre-treatment of EqASCs cells with different concentrations of C. glomerata methanolic extract (1% and 5%) provided a clear protection against cellular damage triggered by H₂O₂. The cell's apoptotic status was significantly regulated, with promotion of cell viability, down-regulation of pro-apoptotic (p21, p53, Bax and Casp-9) genes expression, concomitant to up-regulation of the survival gene Bcl-2, this being supported by a mitigation of the endoplasmic reticulum (ER) stress and significant minimization of mitochondrial dysfunction. The results also showed that C. glomerata extract significantly increased the antioxidant enzymes Superoxide dismutase (SOD) and Catalase (CAT) activities, positively regulated the enzymes genes expression, and markedly reduced the protein carbonyls derivatives production. Finally, RT-qPCR analysis of the inflammatory related genes allowed to highlight a promising anti-inflammatory and immunomodulatory effect of this extract. Due to the valuable antioxidant and anti-inflammatory activities, C. glomerata may have potential benefits for the prevention of equine diseases associated with oxidative stress, including metabolic syndrome.

Effects of zinc deficiency on impaired spermatogenesis and male infertility: the role of oxidative stress, inflammation and apoptosis

Zinc (Zn) is necessary for the normal function of the male reproductive system and spermatozoa. Although influences of zinc deficiency on impaired spermatogenesis and male infertility have been widely considered, the molecular and cellular mechanisms of these abnormalities are not well understood. General abnormalities, including hypogonadism, Leydig cells damage, deficiency of sex hormone production and impaired spermatogenesis, as well as inflammation, antioxidant depletion, sperm death and male infertility can be observed during zinc deficiency. However, it is not obvious which pathways are relevant to the pathogenesis of zinc deficiency. Oxidative stress (OS) induced by reactive oxygen species is likely as the main mechanism of zinc deficiency which is associated with sperm DNA fragmentation, decrease in sperm membrane integrity, apoptosis, depletion of antioxidants, and consequently poor sperm quality and male infertility. Therefore, identification of these pathways will give valuable information regarding the mechanisms of zinc deficiency on the male reproductive system and the potential way for developing a better clinical approach. In this review, we aim to discuss the proposed cellular and molecular mechanisms of zinc deficiency on the male reproductive system, the importance of OS and mechanisms by which zinc deficiency induces OS and depletion of other antioxidants.

Zinc mitigates renal ischemia-reperfusion injury in rats by modulating oxidative stress, endoplasmic reticulum stress, and autophagy

Oxidative stress is a major factor involved in the pathogenesis of renal ischemia/reperfusion (I/R). Exogenous zinc (Zn) was suggested as a potent antioxidant; however, the mechanism by which it strengthens the organ resistance against the effects of reactive oxygen species (ROS) is not yet investigated. The present study aims to determine whether acute zinc chloride (ZnCl₂ ) administration could attenuate endoplasmic reticulum (ER) stress, autophagy, and inflammation after renal I/R. Rats were subjected to either sham operation (Sham group, n = 6), or 1 hr of bilateral ischemia followed by 2 hr of reperfusion (I/R groups, n = 6), or they received ZnCl₂ orally 24 hr and 30 min before ischemia (ZnCl₂ group, n = 6). Rats were subjected to 1 hr of bilateral renal ischemia followed by 2 hr of reperfusion (I/R group, n = 6). Our results showed that ZnCl₂ enhances renal function and reduces cytolysis (p < 0,05). In addition, it increased significantly the activities of antioxidant enzymes (SOD, CAT, and GPX) and the level of GSH in comparison to I/R (p < 0,05). Interestingly, ZnCl₂ treatment resulted in significant decreased ER stress, as reflected by GRP78, ATF-6,p-eIF-2α, XPB-1, and CHOP downregulaion. Rats undergoing ZnCl₂ treatment demonstrated a low expression of autophagy parameters (Beclin-1 and LAMP-2), which was correlated with low induction of apoptosis (caspase-9, caspase-3, and p-JNK), and reduction of inflammation (IL-1ß, IL-6, and MCP-1) (p < 0,05). In conclusion, we demonstrated the potential effect of Zn supplementation to modulate ER pathway and autophagic process after I/R.

The chemo-prophylactic efficacy of an ethanol Moringa oleifera leaf extract against hepatocellular carcinoma in rats

CONTEXT

Hepatocellular carcinoma (HCC) is among the most well-known threatening tumours around the world, and the outlook remains bleak. Moringa oleifera Lam. (Moringaceae) exhibits antitumor, antioxidant and hepatoprotective properties.

OBJECTIVES

To assess the chemo-prophylactic proficiency and other likely activities of Moringa oleifera leaf ethanol extract (MOLEE) against diethyl nitrosamine (DEN)-induced HCC.

MATERIALS AND METHODS

Wistar rats were gastrogavaged with MOLEE (500 mg/kg) for one week and then gastrogavaged with MOLEE and DEN (10 mg/kg) for the following 16 weeks. The progressions of the histological components, serum biomarkers and oxidation of DNA of the liver tissues were resolved to assess the prophylactic impacts. The lipid oxidative biomarker, the cancer prevention agent status and apoptotic proteins were surveyed to assess the potential mechanisms.

RESULTS

The MOLEE LD50 was estimated to be 5585 mg/kg. MOLEE (500 mg/kg) administration fundamentally repressed the expansion event of knobs and the normal knob number per knob-bearing livers prompted by DEN, enhanced hepatocellular appearance and altogether significantly decreased (p < 0.05) DEN-induced elevations in serum biochemical records and hepatic 8-hydroxy-2-deoxyguanosine (8-OHdG) levels by 29%. The robotic studies found that MOLEE disrupted the DEN-activated oxidative reactivity damage in rats by 46.8%. Curiously, the expression of Bcl-2, Bcl-xl and β-arrestin-2 were fundamentally diminished (p < 0.05); however, the expression of Bax and caspase-3 were essentially (p < 0.05) upregulated.

DISCUSSION AND CONCLUSIONS

The outcomes presume that MOLEE inspired critical defensive impacts against DEN-induced hepatocarcinogenesis that might be identified with the implementation of antioxidant activity and actuation of apoptosis.

Knockdown of SLC39A7 suppresses cell proliferation, migration and invasion in cervical cancer

Cervical cancer is the fourth leading cause of malignancy related mortality in women worldwide. SLC39A7 (ZIP7) is a zinc transporter that plays a key role in intestinal epithelial self-renewal. However, whether or not SLC39A7 is involved in human cervical cancer remains unclear. In this study, we investigated the effects of SLC39A7 in cervical cancer in vitro and elucidate related underlying mechanisms. Using Oncomine data analysis, we first found SLC39A7 is commonly upregulated in cervical cancer tissues in comparison with corresponding normal controls. The in vitro experiments indicated that silencing of SLC39A7 expression resulted in decreased cell proliferation, increased cell apoptosis, and attenuated migratory and invasive ability using CCK-8, colony formation, flow cytometry, transwell assays, respectively in cervical cancer cell lines, HeLa and ME-180 cells. In molecular levels, Western blot further demonstrated that silencing of SLC39A7 significantly upregulated the expression of Bax and E-cadherin, downregulated the expression of Bcl-2 and MMP-2 in both HeLa and ME-180 cells. These findings provide evidence that SLC39A7 plays a positive role in the progression of cervical cancer and its knockdown might be as a potential therapeutic target for cervical cancer treatment.

Identification of apoptosis-related genes Bcl2 and Bax from yellow catfish Pelteobagrus fulvidraco and their transcriptional responses to waterborne and dietborne zinc exposure

Apoptosis plays a key role in the physiology of multicellular organisms, and has been well studied in mammals, but not in teleosts. Zinc (Zn) has been shown to be an important regulator of apoptosis and apoptosis involves in the regulation of lipid metabolism. Moreover, our recent study indicated that waterborne and dietborne Zn exposure differently influenced lipid metabolism in Pelteobagrus fulvidraco, but further mechanism remained unknown. The hypothesis of the present study is that apoptosis mediated the Zn-induced changes of lipid metabolism of P. fulvidraco subjected to different exposure pathways. To this end, we cloned full-length cDNA sequences of Bcl2 and three Bax subtypes involved in apoptosis in P. fulvidraco, explored their mRNA expressions in responses to different Zn exposure pathways. Bcl2 and three Bax subtypes shared similar domain structure as typical pro- and anti-apoptotic Bcl2 family members. Their mRNAs were widely expressed among various tissues, but at variable levels. Waterborne Zn exposure down-regulated mRNA levels of Baxg and ratios of Baxa/Bcl2, and Baxg/Bcl2, but showed no significant effects on mRNA abundances of Bcl2, Baxa and Baxb, and the ratio of Baxb/Bcl2. In contrast, dietborne Zn exposure up-regulated mRNA levels of Bcl2, Baxa, Baxb and Baxg, but reduced the ratios of Baxa/Bcl2, Baxb/Bcl2, and Baxg/Bcl2. Considering their important roles of these genes in apoptosis induced by Zn, apoptosis may mediate the Zn-induced changes of hepatic lipid metabolism of Pelteobagrus fulvidraco under different Zn exposure pathways. For the first time, we characterized the full-length cDNA sequences of Bcl2 and three Bax subtypes, determined their expression profiles and transcriptional responses to different Zn exposure pathways, which would contribute to our understanding of the molecular basis of apoptosis, and also provide new insights into physiological responses to different Zn exposure pathways.

MDG‑1 inhibits H2O2‑induced apoptosis and inflammation in human umbilical vein endothelial cells

MDG‑1, a water‑soluble polysaccharide extracted from Ophiopogon japonicus, has been reported to serve a role in antimyocardial ischemia by protecting cardiomyocytes from hypoxia/reoxygenation‑induced damage. However, it remains unknown whether MDG‑1 protects human umbilical vein endothelial cells (HUVECs) against oxidative stress‑induced damage. In the present study, HUVECs were treated with hydrogen peroxide (H2O2) to establish an oxidative stress‑induced cell injury model. Treatment of HUVECs with different concentrations of H2O2 significantly attenuated cell viability and increased cell apoptosis in a time and dose‑dependent manner. Pretreatment with MDG‑1 markedly reduced H2O2‑induced cell death, ROS generation and inflammatory factor secretion. In addition, pretreatment with MDG‑1 decreased the expression levels of proapoptotic proteins BCL2 associated X (Bax) and caspase‑3, while it increased the expression levels of the antiapoptotic protein BCL2 apoptosis regulator (Bcl‑2), compared with H2O2 treatment alone. Taken together, the present data suggest that MDG‑1 protected HUVECs against H2O2‑induced apoptosis and inflammation through inhibition of Bax/Bcl‑2 protein ratio, caspase‑3 expression, and inflammatory factor secretion. This study provides a potential application for MDG‑1 in the treatment of cardiovascular disease.

Capsaicin mediates caspases activation and induces apoptosis through P38 and JNK MAPK pathways in human renal carcinoma

BACKGROUND

Renal cell carcinoma (RCC) is one of the tumors most refractory to chemotherapy to date. Therefore, novel therapeutic agents are urgently needed for this disease. Capsaicin (CPS), a natural active ingredient of green and red peppers, and a ligand of transient receptor potential vanilloid type 1 (TRPV1), has been showed potential in suppression of tumorigenesis of several cancers. Nonetheless, the anti-cancer activity of CPS has never been studied in human RCC.

METHODS

CCK8 analysis, LDH release activity and ROS generation analysis, flow cytometry analysis, and nuclear staining test were performed to test the influence of CPS in cultured cells in vitro, meanwhile western blot was done to uncover the precise molecular mechanisms. 786-O renal cancer xenografts were builded to investigate the antitumor activity of CPS in vivo.

RESULTS

We found treatment of CPS reduced proliferation of renal carcinoma cells, which could be attenuated by TRPV1 representative antagonist capsazepine (CPZ). CPS induced obvious apoptosis in renal carcinoma cells. These events were associated with substantial up-regulation of pro-apoptotic genes including c-myc, FADD, Bax and cleaved-caspase-3, -8, and -9, while down-regulation of anti-apoptotic gene Bcl2. Besides, CPS-treatment activated P38 and JNK MAPK pathways, yet P38 and JNK inhibitors afforded protection against CPS-induced apoptosis by abolishing activation of caspase-3, -8, and -9. Furthermore, CPS significantly slowed the growth of 786-O renal cancer xenografts in vivo.

CONCLUSIONS

Such results reveal that CPS is an efficient and potential drug for management of human RCC.

Inhibition of WWP2 suppresses proliferation, and induces G1 cell cycle arrest and apoptosis in liver cancer cells

Primary liver cancer is one of the most common and aggressive human malignancies worldwide. As numerous studies have revealed that WW domain containing E3 Ub‑protein ligase 2 (WWP2) exerts cancer‑specific functions, the present study assessed the role of WWP2 in liver cancer. WWP2 was revealed to be significantly overexpressed in liver cancer tissues compared with paired normal tissues at the mRNA as well as at the protein level. Furthermore, small interfering RNA-mediated WWP2 knockdown in liver cancer cell lines was demonstrated to inhibit cell proliferation, cause cell cycle arrested in G1 phase and to induce apoptosis as revealed by a Cell Counting Kit-8 assay and flow cytometric analysis. In addition, western blot analysis revealed that WWP2 knockdown significantly increased the expression of apoptosis-associated markers caspase‑7, caspase‑8 and B-cell lymphoma 2 (Bcl-2)-associated X in liver cancer cell lines, while Bcl‑2 was significantly decreased. In conclusion, the present study suggested that WWP2 may exert important functions in the over‑proliferation and evasion of apoptosis of liver cancer, likely through regulating the expression of apoptosis-associated markers. Furthermore, WWP2 may represent a novel diagnostic marker and molecular therapeutic target for liver cancer.

BDNF-TrkB pathway mediates neuroprotection of hydrogen sulfide against formaldehyde-induced toxicity to PC12 cells

Formaldehyde (FA) is a common environmental contaminant that has toxic effects on the central nervous system (CNS). Our previous data demonstrated that hydrogen sulfide (H2S), the third endogenous gaseous mediator, has protective effects against FA-induced neurotoxicity. As is known to all, Brain-derived neurotropic factor (BDNF), a member of the neurotrophin gene family, mediates its neuroprotective properties via various intracellular signaling pathways triggered by activating the tyrosine kinase receptor B (TrkB). Intriguingly, our previous data have illustrated the upregulatory role of H2S on BDNF protein expression in the hippocampus of rats. Therefore, in this study, we hypothesized that H2S provides neuroprotection against FA toxicity by regulating BDNF-TrkB pathway. In the present study, we found that NaHS, a donor of H2S, upregulated the level of BDNF protein in PC12 cells, and significantly rescued FA-induced downregulation of BDNF levels. Furthermore, we found that pretreatment of PC12 cells with K252a, an inhibitor of the BDNF receptor TrkB, markedly reversed the inhibition of NaHS on FA-induced cytotoxicity and ablated the protective effects of NaHS on FA-induced oxidative stress, including the accumulation of intracellular reactive oxygen species (ROS), 4-hydroxy-2-trans-nonenal (4-HNE), and malondialdehyde (MDA). We also showed that K252a abolished the inhibition of NaHS on FA-induced apoptosis, as well as the activation of caspase-3 in PC12 cells. In addition, K252a reversed the protection of H2S against FA-induced downregulation of Bcl-2 protein expression and upregulation of Bax protein expression in PC12 cells. These data indicate that the BDNF-TrkB pathway mediates the neuroprotection of H2S against FA-induced cytotoxicity, oxidative stress and apoptosis in PC12 cells. These findings provide a novel mechanism underlying the protection of H2S against FA-induced neurotoxicity.

Molecular basis for the effects of zinc deficiency on spermatogenesis: An experimental study in the Sprague-dawley rat model

Introduction:

The objective of this study is to investigate the molecular mechanisms underlying the effects of zinc deficiency on spermatogenesis in the Sprague-Dawley (SD) rat.

Materials and Methods:

Three groups of eight adult male SD rats were maintained for 4 weeks on a normal diet as control, zinc deficient diet and zinc deficient diet with zinc supplementation of 28 mg zinc/kg body weight respectively. Using standard techniques, the following parameters were compared between the three groups of experimental animals at the end of 4 weeks: (a) Serum zinc, magnesium (Mg), copper (Cu), selenium (Se) and cadmium (Cd), (b) serum sex hormones, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPX), (c) interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-α), Bcl-2, Bax and caspase-3 expression in the testes, (d) assessment of apoptosis of testicular cells using electron microscopy and (e) testicular volume and histology using the orchidometer and Johnsen score, respectively.

Results:

The zinc deficient group showed a reduction of testicular volume, serum concentrations of Zn, Cu, Se, Mg, SOD, GPX, IL-4, Bcl-2 and testosterone (P < 0.05), as well as increased levels of serum Cd, MDA and tissue TNF-α, Bax, caspase-3 and apoptosis of the germ cells (P < 0.05) compared with control and zinc supplementation groups.

Conclusion:

Zinc deficiency is associated with impaired spermatogenesis because of reduced testosterone production, increased oxidative stress and apoptosis. These findings suggest that zinc has a role in male reproduction.

The effect of zinc and the role of p53 in copper-induced cellular stress responses

Metals can directly or indirectly cause an increase in reactive oxygen species (ROS) accumulation in cells, and this may result in programmed cell death. A number of previous studies have shown that zinc (Zn) modulates mitogenic activity via several signalling pathways, such as AKT, mitogen-activated protein kinase (MAPK), nuclear factor-kappa B (NF -κB), AP-1 and p53. The exact role that Zn plays in the regulation of apoptosis remains ambiguous. Intracellular free Zn modulates p53 activity and stability, and excess Zn alters the p53 protein structure and down-regulates p53's binding to DNA. Copper (Cu) accumulation causes apoptosis that seems to be mediated by DNA damage and subsequent p53 activation. Cu can also displace Zn from its normal binding site on p53, resulting in abnormal protein folding and disruption of p53 function. In spite of the induction of the tumour suppressor p53, hepatic Cu accumulation significantly increases the risk of cancerous neoplasm both in humans and rats, suggesting that p53 function may be impaired in these cells. It is generally understood that imbalances in Cu and Zn levels may lead to a higher prevalence of p53 mutations. An increased number of p53 mutations have been found in liver samples from Wilson's disease (WD) patients. High levels of the p53 mutation most probably contribute to the pathogenesis of cancer in individuals with WD, but the cause and effect are not clear. The protein p53 also plays a crucial role in the transcriptional regulation of metallothionein, which indicates a novel regulatory role for p53. This review discusses the central role of p53 and the redox-inert metal Zn in the cellular stress responses induced by the redox active biometal Cu.

A combination of ascorbic acid and α-tocopherol or a combination of Mg and Zn are both able to reduce the adverse effects of lindane-poisoning on rat brain and liver

The purpose of this study, carried out on male Wistar rats, was to evaluate the beneficial effects of supplementation with ascorbic acid (Vit C) and α-tocopherol (Vit E) or with Mg and Zn upon lindane-induced damages in liver and brain. Under our experimental conditions, lindane poisoning (5mg/kg body weight per day for 3 days) resulted in (1) an increased level of plasma glucose, cholesterol and triglycerides, (2) an increased activity of LDH, ALP, AST, ALT, (3) an oxidative stress in liver and brain as revealed by an increased level of lipids peroxidation (TBARS) and a decrease of glutathione-peroxidase, superoxide dismutase and catalase activities in liver and brain. In conclusion, both Vit C+E or Mg+Zn treatments display beneficial effects upon oxidative stress induced by lindane treatment in liver and brain.

N-terminal cleavage fragment of focal adhesion kinase is required to activate the survival signalling pathway in cultured myoblasts under oxidative stress

We have previously shown that the cultured L6 myoblasts are susceptible to menadione-induced oxidative stress. Damaged cells were detached from the culture dishes. In the present study, we focused on focal adhesion kinase (FAK), which plays pivotal roles in maintaining focal adhesion function and cell survival. FAK, normally localized at the focal adhesion regions of the myoblasts, was not observed at the regions under oxidative stress induced by menadione and H(2) O(2) . Two cleavage products, 80-kDa N-terminal FAK and 35-kDa C-terminal FAK fragments, as well as full-length FAK (125 kDa) were detected in myoblasts cultured under normal conditions by western blotting with anti-N-terminal FAK or anti-C-terminal FAK sera. Of interest was the finding that the cleavage products of FAK (but not full-length FAK) disappeared under oxidative stress. The cleavage of full-length FAK to N-terminal FAK and C-terminal FAK was inhibited by calpeptin, a specific calpain inhibitor. In addition, pre-incubation of cells with calpeptin resulted in a sharp decrease in survival signals, such as Akt phosphorylation and the ratio of Bcl-2/Bax, under stress conditions. By contrast, not only relative viability, but also Akt phosphorylation and the ratio of Bcl-2/Bax was significantly improved when cells were transfected with a DNA construct of N-terminal FAK-Myc. These results suggest that the N-terminal FAK positively regulates survival signalling in early phases of oxidative stress in the cultured myoblasts.

Protective effects of garlic oil on hepatocarcinoma induced by N-nitrosodiethylamine in rats

To investigate the protective effects and the possible mechanisms of garlic oil (GO) against N-nitrosodiethylamine (NDEA)-induced hepatocarcinoma in rats, Wistar rats were gavaged with GO (20 or 40 mg/kg) for 1 week, and then were gavaged with GO and NDEA (10 mg/kg) for the next 20 weeks. The changes of morphology, histology, the biochemical indices of serum, and DNA oxidative damage of liver were examined to assess the protective effects. Lipid peroxidation (LPO), antioxidant defense system, and apoptosis-related proteins were measured to investigate potential mechanisms. At the end of the study (21 weeks), GO administration significantly inhibited the increase of the nodule incidence and average nodule number per nodule-bearing liver induced by NDEA, improved hepatocellular architecture, and dramatically inhibited NDEA-induced elevation of serum biochemical indices (alanine aminotransferase , aspartate aminotransferase, alkaline phosphatase and gamma-glutamyl transpeptidase) and hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in a dose-dependent manner. The mechanistic studies demonstrated that GO counteracted NDEA-induced oxidative stress in rats illustrated by the restoration of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) levels, and the reduction of the malondialdehyde (MDA) levels in liver. Furthermore, the mRNA and protein levels of Bcl-2, Bcl-xl, andβ-arrestin-2 were significantly decreased whereas those of Bax and caspase-3 were significantly increased. These data suggest that GO exhibited significant protection against NDEA-induced hepatocarcinogenesis, which might be related with the enhancement of the antioxidant activity and the induction of apoptosis.

Effects of exogenous hydrogen sulfide on apoptosis proteins and oxidative stress in the hippocampus of rats undergoing heroin withdrawal

In this study, the mechanism of H(2)S protection in the hippocampus of heroin-treated rats was investigated. Male Sprague-Dawley rats were randomly divided into three groups: a saline group, a heroin and saline group, and a heroin and sodium hydrosulfide group. According to the principle of increasing heroin dosage daily, heroin withdrawal was precipitated on day 9 with an injection of naloxone (5 mg/kg, i.p.), and withdrawal symptoms were scored. The levels of cystathionine-β-synthase, H2S, reduced glutathione and malondialdehyde, as well as the levels of cleaved caspase-3, Bax, and Bcl-2 proteins and the activities of superoxide dismutase, catalase, and glutathione peroxidase were assayed in the hippocampus. The results showed that exogenous H(2)S alleviated heroin withdrawal symptoms. Moreover, exogenous H(2)S not only increased cellular H(2)S and the cystathionine-β-synthase protein level activity but also significantly improved heroin-induced oxidative stress. Protein expression of cleaved caspase-3 and Bax decreased, whereas Bcl-2 protein levels in hippocampus increased with exogenous H(2)S. Exogenous H(2)S alleviated heroin-induced rat hippocampal damage through antioxidant and antiapoptosis effects.

Loss of hsp70.1 Decreases Functional Motor Recovery after Spinal Cord Injury in Mice

Heat shock proteins (HSPs) are specifically induced by various forms of stress. Hsp70.1, a member of the hsp70 family is known to play an important role in cytoprotection from stressful insults. However, the functional role of Hsp70 in motor function after spinal cord injury (SCI) is still unclear. To study the role of hsp70.1 in motor recovery following SCI, we assessed locomotor function in hsp70.1 knockout (KO) mice and their wild-type (WT) mice via the Basso, Beattie and Bresnahan (BBB) locomotor rating scale, before and after spinal hemisection at T13 level. We also examined lesion size in the spinal cord using Luxol fast blue/cresyl violet staining. One day after injury, KO and WT mice showed no significant difference in the motor function due to complete paralysis following spinal hemisection. However, when it compared to WT mice, KO mice had significantly delayed and decreased functional outcomes from 4 days up to 21 days after SCI. KO mice also showed significantly greater lesion size in the spinal cord than WT mice showed at 21 days after spinal hemisection. These results suggest that Hsp70 has a protective effect against traumatic SCI and the manipulation of the hsp70.1 gene may help improve the recovery of motor function, thereby enhancing neuroprotection after SCI.

Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia

Circulating monocytes exhibit an apoptotic resistance phenotype during HIV viremia in association with increased MT expression. MTs are known to play an important role in zinc metabolism and immune function. We now show, in a cross-sectional study using peripheral monocytes, that expression of MT1 isoforms E, G, H, and X is increased significantly in circulating monocyte cells from HIV+ subjects during chronic viremic episodes as compared with uninfected subjects. This increase in expression is also observed during acute viremia following interruption of suppressive ART. Circulating monocytes from HIV+ donors were also found to have elevated zinc importer gene Zip8 expression in conjunction with elevated intracellular zinc levels in contrast to CD4(+)T-lymphocytes. In vitro HIV-1 infection studies with elutriated MDM confirm a direct relation between HIV-1 infection and increased MDM MT1 (isoform G) gene expression and increased intracellular zinc levels. A direct link between elevated zinc levels and apoptosis resistance was established using a cell-permeable zinc chelator TPEN, which reversed apoptosis resistance effectively in monocytes from HIV-infected to levels comparable with uninfected controls. Taken together, increases in MT gene expression and intracellular zinc levels may contribute directly to maintenance of an immune-activated monocyte by mediating an increased resistance to apoptosis during active HIV-1 viremia.

The essential toxin: impact of zinc on human health

Compared to several other metal ions with similar chemical properties, zinc is relatively harmless. Only exposure to high doses has toxic effects, making acute zinc intoxication a rare event. In addition to acute intoxication, long-term, high-dose zinc supplementation interferes with the uptake of copper. Hence, many of its toxic effects are in fact due to copper deficiency. While systemic homeostasis and efficient regulatory mechanisms on the cellular level generally prevent the uptake of cytotoxic doses of exogenous zinc, endogenous zinc plays a significant role in cytotoxic events in single cells. Here, zinc influences apoptosis by acting on several molecular regulators of programmed cell death, including caspases and proteins from the Bcl and Bax families. One organ where zinc is prominently involved in cell death is the brain, and cytotoxicity in consequence of ischemia or trauma involves the accumulation of free zinc. Rather than being a toxic metal ion, zinc is an essential trace element. Whereas intoxication by excessive exposure is rare, zinc deficiency is widespread and has a detrimental impact on growth, neuronal development, and immunity, and in severe cases its consequences are lethal. Zinc deficiency caused by malnutrition and foods with low bioavailability, aging, certain diseases, or deregulated homeostasis is a far more common risk to human health than intoxication.

Zinc: the brain's dark horse

Zinc is a life-sustaining trace element, serving structural, catalytic, and regulatory roles in cellular biology. It is required for normal mammalian brain development and physiology, such that deficiency or excess of zinc has been shown to contribute to alterations in behavior, abnormal central nervous system development, and neurological disease. In this light, it is not surprising that zinc ions have now been shown to play a role in the neuromodulation of synaptic transmission as well as in cortical plasticity. Zinc is stored in specific synaptic vesicles by a class of glutamatergic or "gluzinergic" neurons and is released in an activity-dependent manner. Because gluzinergic neurons are found almost exclusively in the cerebral cortex and limbic structures, zinc may be critical for normal cognitive and emotional functioning. Conversely, direct evidence shows that zinc might be a relatively potent neurotoxin. Neuronal injury secondary to in vivo zinc mobilization and release occurs in several neurological disorders such as Alzheimer's disease and amyotrophic lateral sclerosis, in addition to epilepsy and ischemia. Thus, zinc homeostasis is integral to normal central nervous system functioning, and in fact its role may be underappreciated. This article provides an overview of zinc neurobiology and reviews the experimental evidence that implicates zinc signals in the pathophysiology of neuropsychiatric diseases. A greater understanding of zinc's role in the central nervous system may therefore allow for the development of therapeutic approaches where aberrant metal homeostasis is implicated in disease pathogenesis.

Comparison of uptake and neuroprotective potential of seven zinc-salts

Zinc plays an important role as an antioxidant in different cells treated with various kinds of oxidative stressors. Although intracellular Zn(2+) is important in many cellular events, little is known about the cellular uptake of this trace metal and the intracellular status that is required for its optimal function. Since previous reports usually employed only one type of zinc-salt, in this work was compared cellular uptake and antioxidative potential of seven zinc-salts in order to discriminate whether different counterions and ligands may influence its function. Oxidative stress was induced by peroxide or iron in neuronal PC12 cells. We compared uptake of zinc-salts into the labile Zn(2+) pool of PC12 cells as well as their effects on the prevention of cell death, glutathione depletion, lipid peroxidation and ROS production. Zinc-salts provided better protection against oxidative stress-induced in PC12 cultures by peroxide than by iron. Preincubations with zinc-salts displayed better neuroprotection in all cases than coincubations. Zinc-histidine complex was shown to be the most potent compound. Our results indicated that protective effect of zinc is not related to its uptake into PC12 cells, what is indicated by the rather low salt concentrations required for the cell protection and by the observation that despite a superior antioxidant effect of zinc-histidine, the uptake of this salt by PC12 cells was remarkably lower in comparison with other zinc-salts. Although zinc-sulfate exerted weak neuroprotective potential, accumulation of Zn(2+) from this salt within cells was significantly higher compared to other salts. The differences in accumulation of zinc-salts were not specific and unique to PC12 cells, since similar results were obtained in rat primary hepatocytes and endothelial HUVEC cells.

Antiproliferation and apoptosis induced by evodiamine in human colorectal carcinoma cells (COLO-205)

Evodiamine (1), a biologically active alkaloid isolated from Evodia rutaecarpa (known in Chinese as Wu-Chu-Yu), has antioxidant, anti-inflammatory, and anticancer activities. It has recently been demonstrated that the cytotoxic activities of 1 might be due to its ability to inhibit cell growth and induce apoptosis. In this study, we investigated the effects of 1 on growth and apoptosis in COLO-205 cells by MTT assay, fluorescence microscopy, transmission electron microscopy, DNA fragmentation assay, flow cytometry, immunohistochemical analysis, Western blotting, and caspase-3 activity assay. Our data revealed that 1 could significantly inhibit COLO-205 cell proliferation in a dose-dependent manner, and 1-treated COLO-205 cells displayed typical morphological apoptotic characteristics and formation of DNA ladders in agarose gel electrophoresis. The COLO-205 cell cycle was arrested in G(2)/M phase by 1. Meanwhile, 1 increased the expression of Bax and p53, decreased the expression of Bcl-2, lowered the mitochondrial transmembrane potential, and induced the activation of caspase-3. These activities may contribute to the anticarcinogenic action of 1.

Zinc is an essential trace element for spermatogenesis

Zinc (Zn) plays important roles in various biological activities but there is little available information regarding its functions in spermatogenesis. In our current study, we further examined the role of Zn during spermatogenesis in the Japanese eel (Anguilla japonica). Human CG (hCG) was injected into the animals to induce spermatogenesis, after which the concentration of Zn in the testis increased in tandem with the progression of spermatogenesis. Staining of testicular cells with a Zn-specific fluorescent probe revealed that Zn accumulates in germ cells, particularly in the mitochondria of spermatogonia and spermatozoa. Using an in vitro testicular organ culture system for the Japanese eel, production of a Zn deficiency by chelation with N,N,N',N'-tetrakis (2-pyridylemethyl)ethylenediamine (TPEN) caused apoptosis of the germ cells. However, this cell death was rescued by the addition of Zn to the cultures. Furthermore, an induced deficiency of Zn by TPEN chelation was found to inhibit the germ cell proliferation induced by 11-ketotestosterone (KT), a fish specific androgen, 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP), the initiator of meiosis in fish, and estradiol-17beta (E2), an inducer of spermatogonial stem-cell renewal. We also investigated the effects of Zn deficiency on sperm motility and observed that TPEN treatment of eel sperm suppressed the rate and duration of their motility but that co-treatment with Zn blocked the effects of TPEN. Our present results thus suggest that Zn is an essential trace element for the maintenance of germ cells, the progression spermatogenesis, and the regulation of sperm motility.

The important role of the apoptotic effects of zinc in the development of cancers

Zinc is a trace element that is essential for the normal function of cells. It is a cofactor for the structure and function of a wide range of cellular proteins including enzymes, transcription factors, and structural proteins. Recent studies have shown that zinc plays a role in the development of various cancers. Unfortunately no established common relationships of zinc with cancer development and progression have been identified. Zinc is known to have systemic effects such as regulation of the immune system as well as direct cellular effects resulting in regulation of gene expression, bioenergetics, metabolic pathways, signal transduction and cell invasion. Zinc is also reported to regulate cell proliferation and growth. In this review presentation we focus on the effects of zinc that are involved in the regulation of apoptosis in malignant cells. We selected the apoptotic effects of zinc because zinc is reported to both induce apoptosis in some cancers and to protect other cancer cells against apoptosis induced by other factors. The effects of zinc in the regulation of apoptosis appear to be cell type specific. More importantly the reported effects of zinc on cancer cells must be viewed from the perspective of the physiological regulation of zinc homeostasis. Thus one must be mindful of the experimental conditions under which zinc effects are investigated relative to the physiological and pathological conditions of cellular zinc distribution and concentrations that can exist in situ.

Identification of the molecules involved in zebra mussel (Dreissena polymorpha) hemocytes host defense

The invasion of North American waterbodies by the zebra mussel (Dreissena polymorpha) has caused ecological catastrophies in North America. Unfortunately, little is known about this nuisance mollusk and its host defense mechanisms. In this study, 32 expressed sequence tags (ESTs) associated with hemocyte stimulation were obtained from a suppression subtractive hybridization (SSH) cDNA library. This SSH-cDNA library was produced by using a cDNA library of naïve hemocytes as the driver and a cDNA library of hemocytes stimulated with a mixture of microbial antigens namely, lipopolysacchride (LPS), peptidoglycan (PGN), and zymosan (ZYM), as the tester. The driver cDNA was subtracted from the tester to increase the relative abundance of the cDNAs that were induced by stimulations. The putative function of 27 ESTs were obtained by using the homologue searching program BLASTx and BLASTn. Four ESTs encoding the protein product homologous to matrilin (Matrn, AM503947), heat shock protein 70 (HSP70, EU835391), seryl-tRNA synthetase (STS, AM503950), and glycine-rich protein (GRP, AM502279) were selected for a subsequent study using quantitative PCR (qPCR) assays with the RNA extracted from hemocytes stimulated with LPS alone. The results of quantitative PCR with stimulated hemocyte RNA demonstrated that the four candidate genes were upregulated by LPS stimulation. The expression levels of both HSP70 and Matrn genes between naïve and 1-h stimulated hemocyte samples are the most significant with 2.78 and 2.20 fold increases, respectively. The significant changes of GRP and STS genes were observed after 2-h stimulation. The phylogenetic analysis of HSP70 molecule indicated that this protein is phylogenetically close to the HSP70 identified from other mollusks. This study shed light on hemocyte-mediated host defense mechanisms of D. polymorpha.

Apoptosis of mesenchymal cells during the pseudoglandular stage of lung development affects branching morphogenesis

Apoptosis has been implicated as an important process in the development of several organ systems, including limbs, kidneys, and the heart. In developing murine lungs, the authors found that apoptosis was more predominant during the pseudoglandular stage of lung development than during the saccular stage, with 93% of the apoptotic structures in the mesenchyme. Murine lung explants cultured in the presence of zinc chloride and aurintricarboxylic acid, 2 blockers of endonuclease function, showed decreased branching. These observations suggest that apoptosis predominates in mesenchymal cells during the pseudoglandular stage of lung development, and may be important for normal progression of lung branching morphogenesis.

Zinc protects endothelial cells from hydrogen peroxide via Nrf2-dependent stimulation of glutathione biosynthesis

Oxidative stress is one of the main causes of vascular disease. This study aims to investigate the antioxidant activity exerted by zinc in primary rat endothelial cells (EC). Using a 24-h treatment with hydrogen peroxide as a model for oxidative stress, we found that zinc supplementation protects from peroxide-induced cell death via increasing the transcription of the catalytic subunit (heavy chain) of glutamate-cysteine ligase (GCLC) and the concentrations of glutathione (GSH). Conversely, zinc depletion significantly decreased the expression of GCLC and the cellular GSH levels, resulting in an increased susceptibility of EC to oxidative stress. Using confocal microscopy and the RNA silencing technique, we found that zinc upregulates the expression of GCLC by activating the transcription factor Nrf2. Surprisingly, the intracellular zinc sensor, metal-responsive transcription factor-1, is not involved in the zinc-induced expression of GCLC. The present study shows that zinc controls the redox state of EC by regulating the de novo synthesis of GSH. This molecular mechanism may contribute to the elaboration of new nutritional and/or pharmaceutical approaches for protecting the endothelium against oxidative stress.